Bad News: This Week’s Floods Are Not the New Normal

New York’s Hudson Valley ended the week under a flash flood watch. Just days ago, Gov. Kathy Hochul toured the same area where torrential rains washed away bridges and cut off train service to Albany. She called this the “new normal,” but she was wrong.

Even with more severe weather on the way before the week is out, even with Vermont still struggling to recover from historic flooding this week, even with eastern New England facing flood warnings today, this is not normal. There is no normal anymore.

To be clear, this isn’t a criticism of Hochul or anyone else who rightly points out that our climate is changing and the weather patterns of the past no longer help us anticipate the future. In fact, that’s the point. Even if communities could adapt to the intensifying rainfall and rising flood risks — the so-called new normal — that now threatens millions more Americans than a generation ago, they’d still be underprepared for what comes next.

That may be the hardest consequence of climate change: the baselines that we use — aka “normals” — are shifting faster and faster each year. In terms of climate science, “normals” in the U.S. refer to the 30-year averages that the National Oceanic and Atmospheric Administration (NOAA) produces to guide long-term planning. (Think highways, bridges, flood control systems.) The current normal, based on 1991 to 2020 averages, reflects conditions in a world that warmed 1.6 degrees Fahrenheit over pre-industrial temperatures. Earth is now closer to 2.3 degrees warmer.

When it comes to extreme rainfall, that difference matters. The warmer the atmosphere gets, the more moisture it can hold — roughly 4% more per every degree (Fahrenheit) of warming. With more water aloft, the chances of heavy rain go up. And rainfall intensity — the amount of water that comes down during the hours when precipitation is recorded — has climbed sharply in just the past 50 years. Since 1970, Albany recorded a rainfall intensity increase of 18%. Burlington, Vt., recorded a 19% increase. As long as the atmosphere keeps warming, rainfall intensity will keep trending upward.

That’s hard to plan for. The goalposts keep moving. If flood-risk planners build defenses to handle the extremes they just encountered, they are almost guaranteed to be breached by even more extreme rains in the future. The same issues make it hard to plan for heat, coastal flooding — and more or less every condition that climate change makes perpetually more severe.

We can stop this. “Normals” will return when carbon pollution — mainly from burning coal, oil and natural gas — no longer adds to the blanket of CO2 wrapped around the Earth. Whenever that happens, at whatever peak global temperature our planet eventually reaches, whatever our new normal looks like, our world will be hot — certainly hotter than today. The risks of catastrophic flooding will be higher, too. But they won’t keep rising. That means it will be possible, once again, to plan for them using “normals” to help protect our communities and economies. Until then, nothing will ever be truly normal.

Andrew Pershing, Ph.D., is vice president for science at Climate Central. He is an expert on how climate trends and events impact ecosystems and people. He recently led the Oceans and Marine Resources chapter of the fourth U.S. National Climate Assessment.